Medical lasers have been used in various practice areas, such as, for example, urology, neurology, otorhinolaryngology, general anesthetic ophthalmology, dentistry, gastroenterology, cardiology, gynecology, and thoracic and orthopedic procedures. Generally, these procedures require precisely controlled delivery of energy as part of the treatment protocol.
Surgical laser systems utilize a frequency doubled Nd:YAG laser, which operates at 532 nm in a quasi continuous mode at high power levels (e.g., 100 watts) and has been used to efficiently ablate tissue. The frequency doubled Nd:YAG laser can be pumped by CW krypton arc lamps and can produce a constant train of laser light pulses. When ablative power densities are used, a superficial layer of denatured tissue is left behind. At high powers, 532 nm lasers induce a superficial char layer that strongly absorbs the laser light and improves ablation efficiency.
Many surgical laser procedures utilize a surgical probe, which generally comprises an optical fiber and a fiber cap over a distal end of the optical fiber to form a probe tip. A laser source delivers laser energy through the optical fiber to the probe tip where the energy is discharged through the fiber cap and onto desired portions of the targeted tissue.
The laser energy may be directed laterally from the probe tip by reflecting the laser energy off a polished beveled surface at the distal end of the optical fiber. The fiber cap seals a cavity containing a gas (or vacuum) that maintains the necessary refractive index difference for total internal reflection at the beveled surface.
It is important that the fiber cap be free of contaminants on the walls of the interior cavity of the fiber cap that receives the distal end of the optical fiber. Such contaminates can adversely affect the assembly of the probe tip and can lead to failure of the probe tip.